iCloud Notes red "correction" underscore

In the iCloud notes app on my iPhone 13 (IOS 18.1.1), following the most recent update 11/24/24, an inexplicable red underscore "correction" appeared on one of my notes. Rather oddly: a word at the end of a parenthesis, the space following, then the dollar sign for a price notation, on six entries, "Gently) $". I have auto correction, predictive text, and check spelling already shut-off in Settings-General-Keyboard. When I select the correction the explanation is "Unbalanced ')' " or "Unknown variable." What is this?